the trajectories yielding the same work (in the forward and backward transformation), i.e. determining the probability distribution (or density) of an amount of work being exerted by a random system trajectory from to , we can write the above equation in terms of the work distribution functions as follows Note that for the backward transformation, the work distribution function must be evaluated by taking the work with the opposite sign. The two work distributions for the forward and backward processes cross at . This phenomenon has been experimentally verified using optical tweezers for the process of unfolding and refolding of a small RNA hairpin and an RNA three-helix junction. The CFT implies the Jarzynski equality. Notes Non-equilibrium thermodynamics Statistical mechanics theorems